Counterfeiting and piracy of software products and information stored on disc storage media has become a significant problem. The problem is especially acute for compact disc read-only memories (CD-ROMs). CD-ROMs are optical discs that stored data in a read-only format. One difficulty in identifying counterfeit CD-ROMs is the inability to distinguish between CD-ROMs that hold the same information. It is also difficult to determine whether a user is authorized to access a CD-ROM.